The bacterium Bordetella pertussis is the causative agent of whooping cough or pertussis. It is currently routine to immunize infants and small children against B. pertussis with a vaccine comprising whole thermally or chemically inactivated B. pertussis cells. Although such vaccines are widely used and are very effective in inducing protection, such whole cell preparations necessarily contain components which are not necessary to achieve protection and which may in fact cause undesirable side effects in association with immunization. It is, therefore, preferable to identify those cellular components which are essential to immunity and utilize only those required to achieve the desired effect.
B. pertussis exhibits many proteins which are potential candidates for such a component vaccine formulation. Among these are lymphocytosis promoting factor (Morse and Morse, J. Exp. Med. 143: 1483-1502, 1976), filamentous hemagluttinin (Cowell et al, in Robbins et al, eds., Bacterial Vaccines, Thieme Stratton, Inc., N.Y., pp. 371-379); and agglutinogens (Eldering et al, J. Bacteriol. 74: 133-136, 1957). Also of recent interest are a number of virulence--associated cell envelope proteins. (Armstrong and Parker, Infect. Immun. 54: 308-314, 1986); Parker and Armstrong, Rev. Infect. Dis. 10 (Suppl. 2): S327-S330, 1988). One or more of these outer membrane components has previously been used as an adjuvant in a vaccine formulation containing Haemophilus influenza e as the active immunogen (U.S. Pat. No. 4, 474,758). Outer membrane proteins also are present in an acellular pertussis vaccine produced by Takeda by copurification of several pertussis proteins.
Of particular interest to the present invention is an outer membrane protein of 30 kilodaltons. A "virulence associated doublet", referred to as Omp 30/32 has previously been described by Parton and Wardlaw. (J. Med Microbiol. 8:47-57, 1975) A 30 KD fraction of the B. pertussis outer membrane proteins was found to be particularly useful in enhancing immune response to H. influenzae capsular polysaccharide (Monji et al., Infect. Immun. 51: 865-871, 1986). Although the protein per se has been isolated, isolation depends upon chemical separation from the bacterial outer membrane and other outer membrane proteins. There has not previously been a means for producing the protein in large quantities by any other method. The present invention now makes available an alternative means for production of the 30 KD protein in high yield without resort directly to the bacterial source.